Fig. 1. Brains, endocasts, and landmarks.

(A) Casts of the internal bony braincase (endocasts) approximate the size and outer shape of the brain in humans (blue), chimpanzees (green), gorillas (black), and orangutans (orange). (B and C) Asymmetries of the brain, such as frontal and occipital petalias (differential projections of the left and right side indicated by arrows), are observable also on the endocast. (D) In this study, the differences (black lines) between an endocranial landmark configuration (blue spheres) and its relabeled reflection (red spheres) were used as a measure for the magnitude and spatial pattern of shape asymmetry without the need to define a midsagittal plane or any other external reference system.